Diffusion or Facilitated diffusion

Question 1

Factors effecting how a substance is transported

Answer 1

Size (small tend to diffuse )
Solubility in lipids or water ( if dissolve in lipid tends to diffuse )
Presence or absence of charge (need carriers or pores )

Question 2

Why does diffusion occur

Answer 2

Random motion of molecules due to energy they have , which is dependent on temperature . Results in them spreading out reaching a uniform distribution

Question 3

Once reached uniform distribution do the molecules move

Answer 3

Yes movement no longer fuses net changes in concentration because equal numbers are moving in both directions

Question 4

How does facilitated diffusion work

Answer 4

Proteins that only allow specific substance to move through
E.g aminio acid
Proteins carrier have matching shapes
Change shape and molecules passed into cell
Returns to original shape

Question 5

How is protein channel specific

Answer 5

Shape and charge

Question 6

Gated channels

Answer 6

Open and close e.g when specific molecule is present or charge across the membrane eg nerve impulses across neurones

Question 7

Carrier molecules

Answer 7

Found outside surface of membrane substance to be moved into cell or organelle
On inside for transport out of cell
Once picked up a molecule rotated through membrane to other side then release
Specific
Happens because carrier changes shape when actually carrying something
Only take place down a concentration gradient
Doesn’t use energy
Red blood cells have carrier to help move glucose

Question 8

Water

Answer 8

Osmosis through channel protein avoids hydrophobic centre

See fig c

Question 9

Cell membrane

Answer 9

Lysosomes

Question 10

Analyse

Answer 10

Describe +reasoning

Question 11

Starch

Answer 11

Large molecule

Question 12

Visking tubing

Answer 12

Partially permeable membrane